container will start flawlessly on one volume but not the other (btrfs)

TL;DR:
one path works fine (root subvolume, / mount), the other one get's stuck at the libaio fallback (and does not recover):

seafile-mysql  | 2025-10-07 19:17:20+00:00 [Warn] [Entrypoint]: /sys/fs/cgroup///memory.pressure not writable, functionality unavailable to MariaDB
seafile-mysql  | 2025-10-07 19:17:20+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
seafile-mysql  | 2025-10-07 19:17:20+00:00 [Note] [Entrypoint]: Entrypoint script for MariaDB Server 1:10.11.14+maria~ubu2204 started.
seafile-mysql  | 2025-10-07 19:17:20+00:00 [Note] [Entrypoint]: Initializing database files
seafile-mysql  | 2025-10-07 19:17:21 0 [Warning] mariadbd: io_uring_queue_init() failed with EPERM: sysctl kernel.io_uring_disabled has the value 2, or 1 and the user of the 
process is not a member of sysctl kernel.io_uring_group. (see man 2 io_uring_setup).
seafile-mysql  | create_uring failed: falling back to libaio

mounts:

root@server: ~# mount
/dev/nvme1n1p1 on / type btrfs (rw,relatime,ssd,discard=async,space_cache,autodefrag,subvolid=267,subvol=/root@/current)
/dev/sdd on /srv/seafile-docker type btrfs (rw,relatime,space_cache,autodefrag,subvolid=2224,subvol=/seafile-docker@/current)

snippet of container config
(happens with container versions 10.11, 11, 12)

db:
...
  volumes:
    - "${PATH}:/var/lib/mysql"
 ...

two different options for PATH in .env: first works, second doesn't

PATH="/opt/seafile-docker/seafile-mysql/db"
PATH="/srv/seafile-docker/seafile-mysql/db"

After almost going crazy, I narrow down to what I believe is the filesystem/driver/subvolume.

Any pointers how to diagnose (or solve) that problem are appreciated!

root@server: ~# docker --version
Docker version 26.1.5+dfsg1, build a72d7cd
root@server: ~# docker-compose --version
Docker Compose version 2.26.1-4

Start with the shown database volume mapping in the Compose configuration and the two PATH values in .env. Compare container startup logs and mount behavior for the root and /srv/seafile-docker Btrfs subvolumes, using the reported Docker, Compose, and MariaDB versions. Done means the cause is isolated and startup works on both paths, or the limitation and required configuration are documented.